Phenyl hydrazones of thienyl phenyl ketones



United States Patent PHENYL HYDRAZONES OF THIENYL PHENYL KETONES Van R.Gaertner, Dayton, Ohio, assignor to Monsanto Chemical Company, St.Louis, Mo., a corporation of Delaware No Drawing. Application September21, E54 Serial No. 457,556

10 Claims. (Cl. 16733) in which R and R are selected from the classconsisting of hydrogen and alkyl radicals of from 1 to carbon atoms, Yand Y are hydrocarbon radicals free of nonbenzenoid unsaturation andcontaining from 1 to 12 carbon atoms, and n is a number of from 1 to 2.

The present phenylhydrazones are readily prepared by contacting athienyl phenyl ketone, which may have up to two alkyl radicalssubstituted in the thiophene and/or the benzene ring with an appropriatehydrocarbon hy drazine. Examples of the thienyl phenyl ketone hydrazonesprovided by the present invention and having the formula shown above areZ-thienyl phenyl ketone phenylhydrazone, Z-thienyl phenyl ketonel-tert-amyl-l-phenylhydrazone, 2-thienyl-4-tolyl ketonel-naphthylhydrazone, 2-thienyl 4-tolyl ketone 4-tolylhydrazone,5-isopropyl-2- thienyl phenyl ketone benzylhydrazone, 3-, 4- orS-methyl- 2-thienyl phenyl ketone phenylhydrazone, 2,5-dimethyl-3-thienyl phenyl ketone phenylhydrazone, 2-thienyl 4-xylyl ketone,4-biphenylylhydrazone, Z-thienyl phenyl ketone 1-n-dodecyl-l-phenylhydrazone, 2-thienyl 4-tolyl ketone 1,1-diphenylhydrazone, etc.

In preparing the present N-hydroearbon hydrazones the thienyl phenylketone or an appropriate alkyl derivative thereof is mixed with thehydrocarbon hydrazine in the presence or absence of an inert solvent ordiluent and/ or an organic acid compound as catalyst, and the whole ismaintained at ordinary or increased temperature until formation of thehydrazone has been completed. In some instances, particularly whenworking with the more sluggish higher alkylhydrazones or when assuranceof complete reaction is desired, it may be advisable to heat thereaction mixture. Temperatures of up to the refluxing temperature of thereaction mixture may be used; higher temperatures, While permissible,serve no purpose in accelerating the generally very ready condensation.Since formation of the hydrazones proceeds with condensation of one moleof the N-hydrocarbon hydrazine with one mole of the ketone, thesereactants are used advantageously in substantially equimolarproportions. Since the.

hydrazone products are insoluble in water, the use of equimolarproportions of the hydrazine compoundand the ke- 2,841,523 Patented July1, 1958 tone eliminates any otherwise tedious isolating procedures,particularly when no solvent or diluent is employed. However, any excessover the stoichiometric proportions of either reactant may be used,particularly if it is desired to assure complete participation of adifiicultly available reactant. The excess of hydrazine compound or ofthe thienyl phenyl ketone may be readily removed from the reactionmixture by known isolating procedures, e. g., by fractionaldistillation, crystallization or solvent extraction.

When working with the highly reactive hydrocarbon hydrazines orthiophene ketones, it is generally desirable to operate in the presenceof an inert solvent or diluent in order to obtain smooth reaction. Suchsolvents or diluents may be non-carbonylic liquids such as Water, theparafiinic alcohols, ethers, or hydrocarbons, aromatic compounds such asbenzene, xylene, nitrobenzene, or chlorobenzene. For easy manipulation,it is recommended that the diluent employed be one in which at least oneof the reactants is soluble.

The condensation reaction may be accelerated, if desired, by the use ofan organic acid as catalyst. Acids such as acetic, butyric, benzoic or4-toluenesulfonic acid may be used for this purpose in catalyticquantities, say, in amounts of from 0.1% to 2.0% by weight of thereactants.

The present N-hydrocarbon hydrazones are stable compounds which rangefrom oils to waxy or crystalline solids. They are particularly valuableas biological toxicants, e. g., as insecticides, nematocides andfungicides. In the field of agricultural fungicides they are outstandingin their ability to suppress growth of wheat rust without injuring thewheat. The hydrazones herein defined are also efiicient for preventingand retarding fungus growth on plants, fruits, seeds, soils, fur,leather, cotton, wool and organic materials in general. They may beapplied directly to the organic material which is to be treated, butbecause the present hydrazones are effective in extremely diluteconcentrations, it is preferred to incorporate them with a carrier ordiluent.

Fungi'cidal dusts may be prepared by mixing the hydrazones with dustingmaterials such as talc, clay, lime, bentonite, pumice, fullers earth,etc. The hydrazones may be dissolved in organic solvents therefor andthe resulting solutions used as fungicidal or fungi-preventing sprays.More exp ediently a small amount of concentrated solution of thehydrazone in an organic solvent, e. g., cyclohexanone, may be added towater in the presence of an emulsifying agent to form an emulsion andthe oil-' l- Water emulsion thus obtained is employed as a spray.Suspensions or dispersions of the hydrazone in a solvent such as waterare advantageously employed in the treatment of such plant foliage,textiles, leather or other material with which it is not desirable toemploy either a solid carrier or an organic solvent.

Fungicidal compositions comprising the present hydrazones may be appliedonly to the surface of the material to be treated as when treatingfoliage, fur, leather and other comparable impregnable materials uponwhich fungus growth is to be prevented or retarded. In other cases, forexample when it is desired to protect seeds frem soil microorganismsharmful to the seeds and plants, the hydrazone, preferably incorporatedwith solid carriers, may be simply mixed with the seed for protection offruits, seeds, plant tubers, etc. during storage; it may beadvantageousto eltect the treatment by employing baths comprisingaqueous emulsions of the fungicides. Impregnation of textiles with thefungicide is also advantageously effected in baths.

As already stated, the present hydrazones are particularly valuable inthe control of cereal rusts, whereby they function as plantchemotherapeutants against the various leaf and stem rusts of wheat,barley, rye, and oats and other small grain crop plants. Such cerealrusts as the stem rust Puccilzia graminis tritici or the leaf rust P.rubigo-verarrizici or the stripe rust P. glumarum of wheat usuallycannot be controlled by general purpose fungicides. The stem and crownrusts of cats (P. graminis avenue and P. coronata avenue), as well asthe stem rust of rye (P. graminis secalis) or the leaf rust (P. harder)of barley display similar resistance.

in prior art, much effort has been expended in the past in breedingrust-resistant strains of these cereals; but as new strains of, e. g.,wheat, are developed, new races of tl e above classes of rusts appearand proceed to attack the new, presumably rust-resistant strains ofwheat. The history of breeding for rust resistance thus comprises arecurrent introduction of cereal strains which are resistant toprevailing races of the rusts and subsequent ap pearance of new races of=rusts to which the recently introduced cereal strains are susceptible.Accordingly, the eradication of fungus growth by chemical treatment ofcereal plants has become subjected to'close scrutiny. Unfortunately mostof the known fungicides have been found to be unsuitable either becausethey do not prevent or destroy rust growth at non-phytotoxicconcentrations or because their physical and chemical nature prevents acommercially expedient means of application. Particularly when aerialdusting or spraying is the contemplated means of application, particlesize and solubility are of extreme importance.

The invention is further illustrated, but not limited, by the followingexamples:

Example 1 2-thienyl phenyl ketone (18.8 :g., 0.1 mole) was dissolved in50 ml. of alcohol by heating to reflux. After some cooling of thesolution there was added to it about 5 ml. of acetic acid, and then 108g. (0.1 mole) of phenylhydrazine was introduced dropwise. When theresulting -xotherrnic reaction had subsided, the reaction mixture washeated briefly to boiling. The whole was allowed to remain at roomtemperature and dried by evacuation. The dried, viscous oil thusobtained comprised the substantially pure 2-thienyl phenyl ketonephenylhydrazone.

Example 2 The therapeutic effect on wheat of the 2-thienyl phenyl ketonephenylhydrazone of Example 1 was determined as follows:

Five uniform, six-day old seedlings of a rust-susceptible variety ofwheat (Seneca) were sprayed with water by 7 means of an atomizer. Theindividual leaves were then gently rubbed between the thumb and indexfinger to remove the bloom, and then inoculated with Pucciniarubigo-vera tritici by gently scraping, up and down the back sides ofthe rubbed leaves, a scalpel which had been water-wetted and loaded withspores of the organism. Following inoculation, the plants were sprayedwith a fine mist of water and maintained for 48 hours in an incubationchamber at a temperature of 70 F. and a humidity of 100%. They were thentransferred to greenhouse benches where they were kept for another 48hours. At the end of that time they were sprayed with an emulsionprepared as follows:

The phenylhydrazone (100 mg.) was added to 5 ml. of acetone, and therewas then introduced to the resulting solution approximately 0.1 ml. ofan emulsifying agent known to the trade as Tween 20 and reputed to be apolyoxyethylene sorbitan monolaurate. The wholewas then diluted with 5ml. of water to give an emulsion containing 1% by weight of thehydrazone. For the instant test the 1% emulsion was further diluted withwater to give'an emulsion containing 0.5% by weight of thephenylhydrazone.

Spraying of the plants with the emulsions was effected by means of anatomizer, 5 ml. of the emulsion being used per pot of 5 plants. Thesprayed plants were then returned to the greenhouse and held there for aweek. Observation of the plants at the end of that time disclosed thatdevelopment of rust on plants which had been sprayed with the emulsionof 2-thienyl phenyl ketone phenylliydrazone had been suppressed, andthere was no evidence of phytotoxic effect. Similarly inoculated butunsprayed plants which had been maintainedin the incubator andgreenhouse for the same length of time were found to be badly affectedby the rust. f

What 1 claim is:

l, A compound having the formula in which R and R are selected from theclass consisting of hydrogen and alkyl radicals of from 1 to 5 carbonatoms and n is a number of from 1 to 2.

2. The phenylhydrazone of thienyl phenyl ketone.

3. Z-thienyl phenyl ketone phenylhydrazone.

4. A biological toxicant comprising an inert carrierand as the essentialactive ingredient a compound having the formula H i re? in which R and Rare selected from the class consisting of hydrogen and alkyl radicals offrom 1 to 5 carbon atoms and n is a number of from 1 to 2.

5. A wheat rust eradicant composition comprising an inert carrier and asthe essential active ingredient a rustinhibiting quantity of a compoundhaving the formula in which R and R are selected from theclassconsisting of hydrogen and alkyl radicals of from 1 to 5 carbonatoms and n is a number of from 1 to 2. i

6. A wheat rust eradicant composition comprising an oil-in-wateremulsion of a rust-inhibiting quantity of thienyl phenyl ketonephenylhydrazone.

7. A wheat rust eradicant composition comprising an oil-in-wateremulsion of Z-thienyl phenyl ketone phenylhydrazone.

8. The method of inhibiting the development of rust on wheat whichcomprises applying to the wheat a rustinhibiting quantity of a wheatrust eradicant composition comprising as the essential active ingredienta compound having the formula in which R and R are selected from theclass consisting of hydrogen and alkyl radicals of from 1 to 5 carbonatoms and n is a number of from 1 to 2.

9. The method of inhibiting the development of rust on wheat whichcomprises applyingto the wheat a rustinhibiting quantity of a wheat rusteradicant composition comprising thienyl phenyl ketone phenylhydrazoneas the essential active ingredient.

10. The method of inhibiting the development of rust on wheat whichcomprises applying to the wheat a rustinhibiting quantity of a wheatrust e-radicant composition comprising Z-thienyl phenyl ketonephenylhydrazone as the essential active ingredient.

References Cited in the file of this patent UNITED STATES PATENTS2,606,166 Patrick Aug 5, 1952

1. A COMPOUND HAVING THE FORMULA
 4. A BIOLOGICAL TOXICANT COMPRISING AN INERT CARRIER AND AS THE ESSENTIAL ACTIVE INGREDIENT A COMPOUND HAVING THE FORMULA 